Letters from popes, archbishops and theologians were an important category of writing in the middle ages. The Registrum or letter-book of Gregory I (the Great; pope 590-604) survives in many copies made during the middle ages. Gregory's correspondence was especially important to English churchmen because he was the pope who sent Augustine on his mission to convert the Angles. This copy of Gregory's letter-book was probably at Rochester cathedral priory from the 12th-century. The church of St Andrew, Rochester, was founded in the earliest days of Augustine's mission. The letters would have been read as historical and legal records, source material for sermons and theological commentaries and probably for personal study and contemplation.

Gregory's letters reveal the variety of ways in which he served the mission of his church. In the three short notes on this page, he first admonishes an aristocratic pilgrim, Rusticiana, of Constantinople, who had just returned from Mount Sinai, for spending to little time contemplating the Holy Land's monuments. The next letter attempts to heal a dispute with John, bishop of Ravenna, over the wearing of the pallium (archbishop's stole) during litanies. The last urges two churchmen--Felix the bishop and Cyriacus the abbot--whom he had sent to Sardinia to push forward the conversion of the natives--to quickly resolve the complaints of Theodosia, a woman who had provided resources for the founding of a monastery.